The present invention relates to steering columns and more particularly to systems and methods for attaching and releasing a steering column assembly to a structure of a vehicle.
In today's world, motor vehicles are commonly equipped with safety features configured to dissipate kinetic energy in the event of an impact between a vehicle occupant and an aspect of a vehicle interior. For example, a steering column may be configured to deform, and thereby absorb energy, while exerting a resistive force upon a vehicle occupant. During normal operation, the steering column may be fixed to the vehicle structure by a structural connection, which may be provided by one or more steering column couplers. Such couplers are typically configured so as to satisfy a number of mechanical or structural design criteria including providing sufficient mechanical strength to withstand both static and dynamic loads associated with normal operation of the vehicle. A steering column coupler may also be configured so as to withstand cyclic stresses and fatigue that may be encountered during the life of the vehicle. Design criteria such as these tend to call for steering column couplers having at least a minimum level of strength.
To facilitate deformation of, and energy absorption by, the steering column, the steering column couplers must also be designed to release in the event of a vehicle collision. For that reason, the steering column couplers are often configured so that the failure strength of the couplers is less than the force that is likely to be exerted on the steering column couplers by a vehicle occupant in the event of a vehicle collision. At the same time, so as to avoid unintended releases, the failure strength of the couplers must be greater than forces that are likely to be exerted on the steering column couplers through incidental contacts with vehicle occupant. Still further, the failure strength of the couplers tends to be increased so as to meet mechanical strength and durability requirements described above. As a result, conventional steering column couplers may require break away forces that are greater than would otherwise be desirable, imposing excessive and possibly injurious loads upon vehicle occupants in the event of a vehicle collision.
Accordingly, it is desirable to have an improved system and method for coupling a steering column assembly to a vehicle structure providing acceptable structural integrity and design life while also facilitating release at acceptable loads upon the occurrence of an impact event.